Posted: 12/28/2009 7:51:41 PM EDT
|
Okay, so I'm confident that GD will answer this clearly-foolish thermography question in no time flat.
Why is it that glass surfaces appear opaque when viewed through a thermal imager, but mirrors still reflect back a thermal image perfectly? Depending on the type of mirror (such as a normal silver glass mirror), wouldn't the outer layer of glass in the mirror itself block the infrared? |
|
The reason it should appears opaque is because you are essentially getting a reading of the material behind the glass, taken at the boundary, which is the glass. If that makes any sense. However, glass will reflect back a thermal image of their surroundings pretty damn well depending on the conditions. Did a thermal inspection of a greenhouse complex as a semester project a while back, and we had a hell of a time getting a good, useable image.
As for your question, technically what the camera sees is just IR Radiation, which is part of the electromagnetic spectrum. So a mirror reflects it just like it reflects visible light. And its not reflecting off the glass bit, but rather the polished silver backing. |
|
Quoted:
Okay, so I'm confident that GD will answer this clearly-foolish thermography question in no time flat. Why is it that glass surfaces appear opaque when viewed through a thermal imager, but mirrors still reflect back a thermal image perfectly? Depending on the type of mirror (such as a normal silver glass mirror), wouldn't the outer layer of glass in the mirror itself block the infrared? Glass will reflect an image in a thermal imager if you are at the right angle. A glass mirror is no different than a glass window other than you do get a little reflectivity out of the back of a mirror. Glass does not appear opaque, it reflects the image in front of it. An imager will only show the surface temps or reflections of objects. |